Resistance element



27, R. R. DUNLOP 5,

RES I STANCE ELEMENT Filed March 8, 1924 Patented Aug. 27, 1929.

UNITED STATES 1,726,476 PATENT OFFICE.

ROBERT R. DUNLOP, OF COLUMBUS, OHIO, ASSIGNOR TO THE JEFFREY MANUFACTUR-ING COMPANY, OF COLUMBUS, OHIO, A CORPORATION OF OHIO.

RESISTANCE ELEMENT.

Application filed March 8, 1924. Serial No. 697,795.

The present invention relates to certain new and useful improvements inresistance elements adapted to use with electrical apparatus subject tothe severe service conditions encountered in electric traction, miningmachinery, and the like.

The especial object of this invention is to provide a wire resistanceadapted to withstand the high temperature and mechanical strains, havingthe necessary electric qualities combined with economy of manufacture,durability under the most severe service conditions, and convenience ofapplication to the apparatus of which it forms a part.

The means whereby I attain this objectare fully set forth in thefollowing specification and illustrated in the accompanying drawings ofwhich Fig. 1 is a side elevation of the preferred embodiment of myinvention.

Fig. 2 is a plan view, partly in section, of the devices illustrated inFig. 1.

Fig. 3 is a fragmentary sectional view taken along the line III of Fig.1.

Fig. 4 is a cross section taken along the line IVIV of Fig. 1.

Like numerals refer to similar parts in the several figures.

As shown in the drawings my improved resistance element comprises aresistance wire 1, preferably formed of metal having high specificelectric resistance combined with heat resisting qualities, which iswound in a laterally flattened coil, and is mounted upon a framework ofpeculiar construction. The supporting framework comprises the end bars 2and the longitudinally extending rods 3 which project through suitableapertures in said end bars and are insulated therefrom by the insulatingtubes 4. which may be formed of any preferred heat resisting insulatingmaterial. Mounted upon the tubes 4 are series of collars 5, preferablyformed of porcelain or other approved heat resisting insulatingmaterial, the peripheries of which approximately conform to and engagethe curved ends 6 of the loops of the resistance wire 1. On each of thecollars 5 is formed a flange 7 adapted to extend between adjacent turnsof the wire 1, and of sufiicient thickness to insure the desired spacedrelation of said turns. Suitable insulating washers 8 and 9 are mountedupon the tubes 4 at the sides of the bars 2, and nuts 10, threaded tothe rods 3, serve to clamp the several elements securely together.Attachment members 11, which may be of any preferred form, mounted uponthe rods 13 between the washers 9 and the nuts 10, afford means for theattachment of my improved resistance unit to any suitable and convenientsupport. The ends of the wires 1 are preferably connected to the endbars 2 which are provided with suitable binding posts 12 for theirconnection with the conductors of an outside circuit. In the drawings Ihave shown the method of attaching the Wires 1 to the bars 2. As hereshown the wires 1 are clamped under the lugs 13 formed on the bars 2 andare secured thereto by soldering, electric welding, or other preferredmechanical means.

In the above described devices I have provided a wire resistance elementhaving approved electrical and mechanical properties of relativelyinexpensive construction extreme durability and reliability in service,and of such flexible design that it may be readily adapted to thelimitations of the apparatus with which it is to be used.

What I claim is 1. In a resistance unit, the combination wit-h aresistance wire wound in an open coil, of a supporting frame thereforcomprising end members electrically connected with said wire, rodsextending longitudinally of said coil through apertures of said endmembers, a continuous insulating tube mounted on each rod and extendingsubstantially from end to end thereof and through said end men"- bers. aplurality of insulating collars mounted upon said tubes to engage theloops of said coil, a flange formed upon each collar projecting betweenadjacent loops, and means to clamp said end members against said collarsas and for the purpose set forth.

2. In a resistance unit, the combination with a resistance wire wound inan open coil, of a supporting frame therefor comprising end memberselectrically connected with said wire, means upon said end members toconnect them with the conductors of an external circuit, rods extendinglongitudinally of said coil through apertures of said end members, acontinuous insulating tube mounted on each rod and extendingsubstantially from end to end thereof and through said end members, aplurality of insulating collars mounted upon said tubes to engage theloops of said coil, a flange formed on each collar projecting betweenadjacent loops, and

nuts threaded upon said rods adapted to clamp said end members againstsaid collars as and for the purpose set forth.

3. In a resistance unit, the combination With a frame includingelectrical conductor end members, rods extended through said endmembers, a continuous insulating tube mounted on each rod and extendingsubstantially from end to end thereof and extended through said endmembers to insulate them from said rods, and a resistance element woundin open coil upon said insulated rods and having its ends electricallyconnected t said conductor end members.

4. In a resistance unit, the combination with a frame includingelectrical conductor end members, rods extended through said endmembers, a continuous insulating tube mounted on each rod and extendingsubstantially from end to end thereof and extended through said endmembers to insulate them from said rods, a resistance element wound inopen coil upon said insulated rods and having its ends electricallyconnected to said conductor end members, attachment members mounted uponsaid insulating tube and being insulated from said end members, andmeans on the ends of the rods for clamping the supporting and attachmentmembers in position.

5. In a resistance unit, the combination with a frame includingelectrical conductor end members, each having a. pair of aperturedspacing bosses, rods extended through said bosses, a continuousinsulating tube mounted on each rod and extended through said aperturedbosses to insulate said con- ROBERT E. DUNLOP.

